Expansion and compression joints for road surface layers



Oct. 15, 1963 H; HAMEL 3,106,879

EXPANSION AND COMPRESSION JOINTS FOR ROAD SURFACE LAYERS Filed Jan. 50, 1961 IN VENTOR 0/ 1/95 flame/ ATTORNEYS United States Patent 3,106,879 EXPANSION AND COMPRESSION JOINTS FOR ROAD SURFACE LAYERS Denis Marcel Henri Hamel, St. Maude, France, assignor to Pneumatiques et Caoutchouc Manufacture Kleber Colombes, Colombes, Seine, France, a French body corporate Filed .lan. 30, 1961, Ser. No. 85,833 Claims priority, application France Feb. 2, 1960 3 Claims. (Cl. 94-18) The present invention relates to expansion and compression joints for road surface layers.

With the object of preventing the formation and/or growth of cracks and fissures in concrete slab surface layers for roads, and the like, it is customary to provide means for maintaining the concrete slabs under substantial compression. Such means may assume various forms, such as tensioned wire cables, hydraulic jacks, inflated rubber bladders and the like.

Where inflated bladders are used, the bladders are of tubular shape and are positioned transversely of the road at spaced intervals of say 50 or 100 meters along the road. With the high grades of rubber currently available it is found possible to provide such inflatable tubes capable of retaining an inflation pressure of say 50 kg./ sq. cm. (about 700 p.s.i.) for periods of months without requiring reinflation. The inflated tubes impose considerable force on the concrete slabs for retaining them under compression.

Similar devices are also used as expansion joints for concrete structures to compensate for the dimensional variations of the concrete, as between hot and cold weather periods, and maintain the compression in the concrete substantially constant.

Usually the rubber bladder or tube is inserted between two metallic channel sections having their webs positioned vertically face to face between adjacent slabs so as to transmit the inflation pressure from the tube to both slabs. The channels are of ditferent sizes and are interfitted to permit relative sliding movement of the channels towards and away fromeach other.

The conventional arrangement just described has a drawback in that the rubber tubing is liable to get caught and pinched between the adjacent channel flanges. Also, under the high pressures obtaining in the tubing the rubher is sometimes apt to flow into the narrow space between adjacent flange surfaces.

According to this invention the difliculty is very simply overcome by inserting in the variable-width spaces defined between the pair of channels, rubber filler strips each having their outer side face applied against the inner surface of a related flange of the larger of the channel, and having an outer side edge pressed against the inner surface of the web of said larger channel by the end surface of a flange of the smaller channel acting against the opposite side edge surface of the strip.

The filler strips are so dimensioned that they will at all times remain under compression, so that there will, at no time, be any clearance space between the rubber strip and the end surface of the smaller channel flange, or between the rubber strip and the inner surface of the larger channel web, even when the two channels are spaced apart the maximum amount.

Since rubber is substantially incompressible, any variation in one dimension of the strip due to a variation in the relative spacing of the channels, necessarily results in a corresponding and opposite variation of the strip dimension normal to said one dimension. Thus as the strip is extended in width its thickness is reduced and vice-versa.

In order that the present invention may be more clearly understood, reference will now be made to the accompanying drawing, which shows a cross sectional view, on

' accordance with the invention.

3,106,879 Patented Oct. 15, 1963 a plane parallel to the longitudinal direction of a road, of one embodiment of road surface joint constructed in It is understood that the length dimension of the joint is disposed transversely across the road.

Upon the road foundation 1 there is placed a concrete slab surface covering 15 cm. deep divided into sections meters long. The FIGURE shows two adjacent slab section-s 2 and 3. The adjacent end surfaces of the sections are lined with metal sheets 4 and 5 suitably anchored in the concrete of the related slab sections.

A rubber bladder or tube 6 inflated to a pressure in the range from 35 to 50 kg/sqcm. is interposed in the space between two facing channels 7 and 8 of adequate size and strength and so dimensioned as to interfit for comparatively free relative sliding movement toward and away from each other.

In accordance with the invention filler means are provided for sealing off :all adjacent surface portions of the inner cavity between the channels, that would otherwise be movable with respect to one another on relative displacement of the channels, and would thus afford a danger of pinching and/or shearing a wall of the inflated tube 6. The filler means comprise the pair of rubber strips 9 and '10 extending along the inner surfaces of the flanges of the larger channel 8, between the web of said channel and the ends of the respective flanges of the smaller channel 7. The strips used are wide enough to provide a substantially continuous surface for the cavity regardless of the spacing between the channels. When the channels shift inwards, the rubber strips being compressed laterally expand inwards of the cavity owing to the incompressible nature of rubber, thereby very slightly increasing the inflation pressure without adverse eifects.

Under the conditions previously specified herein, a set of suitable dimensions for the rubber tube 6 may comprise an outer diameter of about mm., and a 'Wall thickness of '10 mm.

Laboratory and field tests have been carried out in which equipment embodying the compression joint of the invention was exposed to stresses and displacements simulating several dozens of years of actual service. The tested equipment showed outstandingly good behaviour in all the tests, whereas a similar joint including the same inflated tubing and channels but minus the rubber filler strips of the invention is generally put out of commission at the end of one or two years.

To facilitate installation, the strips 9 and 10 may be attached to the larger channel 8 as by vulcanisation or with an adhesive bond. The bond may be provided only along the narrow side edge of the strip or it may further encompass :an adjacent portion of the larger side of the strip. In a modified form, the strips 8 and 9 may be bonded to the inflatable tube 6 rather than to a channel. In one embodiment, the inflatable tube is formed integrally with two projecting ribs or beads to provide the tiller strips 9 and 10 of the invention, the entire molded assembly having a uniform and homogeneous structure throughout its cross section.

Various other modifications may be conceived without departing from the spirit of the invention.

I claim:

1. An expansion and compression joint for road surface layers and the like, comprising a pair of metal channel members, one of said channel members being of smaller size than the other and the channels facing each other with the flanges of the smaller channel member fitting between those of the larger to provide for free sliding movement of the channel members towards and away from each other, a pair of filler strips of elastic material posi- 3,106,879 3 4 tioned respectively in the inner corner areas of the larger 3. A joint as claimed in claim 1, wherein the elastic channel member and engaging the adjacent ends of the filler strips are unitary with the inflatable tube. flanges of the smaller channel member with said strips being always in compressed condition, and an inflatable References Cited in the mg of this Patent tube in the enclosed space defined :by said channels and 5 UNITED STATES PATENTS filler strips and in contacting relationship with the respec- 3 3 7 Heltzel O t, 18, 1938 tive surfaces defining said space. 2,251,672 Friberg Aug. 5, 1941 2. A joint as claimed in claim 1, wherein the elastic 2,351,255 Fischer June 13, 1944 filler strips are secured to the larger channel member. 2,910,921 Freyssinet Nov. 3, 1959 

1. AN EXPANSION AND COMPRESSION JOINT FOR ROAD SURFACE LAYERS AND THE LIKE, COMPRISING A PAIR OF METAL CHANNEL MEMBERS, ONE OF SAID CHANNEL MEMBERS BEING OF SMALLER SIZE THAN THE OTHER AND THE CHANNELS FACING EACH OTHER WITH THE FLANGES OF THE SMALLER CHANNEL MEMBER FITTING BETWEEN THOSE OF THE LARGER TO PROVIDE FOR FREE SLIDING MOVEMENT OF THE CHANNEL MEMBERS TOWARDS AND AWAY FROM EACH OTHER, A PAIR OF FILLER STRIPS OF ELASTIC MATERIAL POSI- 